The present invention relates to a coating applicator for applying a layer of coating material to an internal surface of a member, such as on the surface of a bore within an elongated element.
Various different coating apparatuses for coating elongated members, such as pipes and bolts, have been developed in the prior art. One type of system includes a chamber which is passed along an elongated member while coating material is applied through grooves within the chamber for coating the elongated member. Such systems are illustrated in U.S. Pat. Nos. 2,305,005 issued to R. E. Henry; 2,429,915 issued to W. H. Bell; and, 2,892,441 issued to D. E. Stearns.
Another type of system was developed by the assignee of the present application as shown in U.S. Pat. No. 3,795,224 issued to R. E. Batson et al, for coating a plurality of headed bolts. In this system, the bolts are conveyed along an assembly line and pass by a coating block which dispenses coating material into contact with the bolts. This system is designed for mass production coating of elongated members and thus, the members to be coated are rapidly conveyed along the conveying path past the coating station. As the members are so conveyed, they are rotated by the conveyor so that the applied coating material is smoothed on and spread evenly around the circumference of the bolt.
None of the above systems, however, are involved with providing a semi-automatic coating applicator for coating a limited number of elongated members. One previously developed system involved with such an objective, was developed by the assignee of the present application. In this system, a bolt was inserted through an opening in the chamber. After the bolt was inserted, a valve mechanism allowed coating material to flow through a plurality of apertures on the interior surface of the chamber so as to come into contact with the circumference of the bolt. The coated bolt was then removed by hand and another bolt inserted. Thus, the flow of coating material was controlled by a valve member located in the feedline for the coating material so that coating material only flowed when the valve was opened after insertion of the bolt.
In order to provide a semi-automatic coating applicator, another system was developed as disclosed in U.S. Patent Application Ser. No. 646,801, to Robert Cotter (the applicant of the present application) and Martin Cosgrove, which has been filed on the same day as the present application. The system disclosed in that application is directed to coating the external surface of an elongated member.
In the coating applicator disclosed in the Patent Application to Robert Cotter and Martin Cosgrove, a coating chamber having an opening for receiving the elongated member which is to be coated, is filled with coating material. The opening has dimensions just slightly larger than the cross-section of the elongated member, so that there can be a close fit of the member within the opening. A retractable cover member is arranged within the chamber for preventing coating material from leaking out of the chamber through the opening. Upon insertion of the elongated member through the opening into the chamber, the cover member is retracted so as to allow coating material to totally surround the entire circumference of a limited longitudinal portion of the elongated member. A coating layer is then applied to the elongated member. After the elongated member has been coated, the member is removed from the chamber. Due to the dimensioning of the inner walls of the chamber, as the coated member is removed, the walls serve to remove excess coating material and to smooth the coating material on the member. After the elongated member has been coated, the member is automatically ejected from the chamber. Immediately prior to the ejection of the elongated member, the cover member is returned to its initial position so as to prevent leakage of coating material through the opening.
While any type of coating material could be applied by the coating applicator illustrated in the above-noted Patent Application, the coating material primarily of concern is a slurry containing an adhesive material. The coating material contains a solvent, which is generally water or another solvent which can be easily driven off if the coated layer on the elongated member is to be dried.
Since many members, such as bolts, which are to be coated originally come from the factory with a thin layer of oil or grease on their exterior surfaces, it is necessary to first remove this layer before applying the coating material. This factor is well known in the prior art and in fact is discussed in the U.S. patent to Batson et al. For this reason, the elongated members are first degreased by any type of conventional degreasing equipment so as to provide a clean surface for good adhesion for the coating material. The degreased members are then supplied with a coating layer by the coating applicator of the present invention. Subsequently, a thin layer of oil can again be supplied to the exterior surface of the elongated member and the coated area. The re-application of the oil, however, is an optional process depending upon the particular use to be made of the member and the period of time before such use. The coated and oiled members can then be dried in an oven so as to substantially drive out any solvent present in the applied layer of coating material.
Those coating systems described above are concerned with coating an external surface of a member. Other coating systems, however, have been developed for coating internal surfaces of a member. These systems generally include an applicator nozzle having an opening in its tip, which is inserted into the bore of the member to be coated. Once the applicator is inserted, a pressure valve is opened thereby allowing material to flow through the applicator and out of the opening. The coating material then comes into contact and coats the internal surface of the bore. These systems are typically hand-operated systems in that either the applicator must be hand held and placed into contact with the internal surface of the bore or the bore member must be hand held in contact with the applicator. Consequently, the rate at which members can be coated is significantly limited with these types of systems.